Embodiments relate to an anti-fuse array of a semiconductor device and a method for forming the same, and more particularly to a technology for manufacturing an array anti-fuse.
In recent times, as information media such as computers have rapidly come into widespread use, technology of a semiconductor device has been rapidly developed. Functionally, it is necessary for a semiconductor device to operate at a high speed and to have a high storage capacity. Therefore, technology for manufacturing semiconductor devices has rapidly developed to improve an integration degree, reliability, a response speed, etc.
A process for manufacturing semiconductor devices includes a fabrication (FAB) process that forms cells, each having integrated circuits by stacking predetermined circuit patterns on a silicon substrate, and an assembly process that packages the substrate into unit cells. An Electrical Die Sorting (EDS) process for testing electrical characteristics of cells formed over the substrate is performed between the FAB process and the assembly process.
The above-mentioned EDS process determines whether the cells formed over the substrate are in an electrically good condition, or are defective. The EDS process removes defective cells before the assembly process, such that efforts or costs consumed in the assembly process may be reduced. As a result, defective cells may be detected by the EDS process in early stages of manufacture and repaired.
Repair processes may be performed as follows.
In order to increase a production yield of the semiconductor device in which a defect has occurred in the fabrication process, a redundant cell is added as a substitute for a defective cell. A fuse for coupling the redundant cell to the integrated circuit is also added in the manufacturing process of the semiconductor device. The repair process replaces the defective cell with the redundant cell in the chip using a fuse for cell recovery. That is, the repair process cuts a specific fuse coupled to the redundant cell, so that a connection originally coupled to the defective cell can be redirected to the redundant cell.
However, although the repair process for repairing defective cells at a wafer level is performed, a 1-bit or 2-bit defect can still unexpectedly occur at a wafer level after execution of the packaging process. An error rate after packaging is about 10%. Thus, an additional repair process may occur after execution of the packaging process. However, since it is difficult to use a laser repair device after completion of the packaging process, there is needed a new fuse different from that of the repair process performed before the packaging process.
The fuse for use in the repair process after the packaging process will hereinafter be described in detail.
The fuse used after the packaging process is generally called an anti-fuse that performs repairing through interconnection instead of disconnection. A fuse used before the packaging process is designed to perform repairing through such disconnection. That is, the term “anti-fuse” is a relative meaning with respect to the fuse used before the packaging process. The anti-fuse is electrically opened at a normal state. However, if a high voltage is applied to the anti-fuse at the normal state to rupture an insulator contained conductors of the anti-fuse, the anti-fuse is coupled to a cell. The anti-fuse is formed in a periphery region (or a peripheral circuit region), and redundant cells for the anti-fuse are also formed in the periphery region, and such redundant cells may be formed as SRAM cells that do not require refresh operation.
The anti-fuse has a variety of advantages. For example, the anti-fuse may allow the repair process to be performed at a package level, may increase a number of net dies, may improve product characteristics, and may overcomes a limitation due to high dependence on device and fabrication which can be found in a conventional laser fuse. Because of the above-mentioned characteristics of the anti-fuse, it is expected that the anti-fuse will be widely used in various technical fields. For the anti-fuse to stably operate, it is important to securely rupture the insulator.